This invention relates generally to the field of radiographic detection systems, and more particularly to coherent x-ray scattering systems using a high resolution x-ray collimator to detect the presence of explosive materials and illicit narcotic substances.
Numerous screening systems have been developed for inspecting cargo such as bags, suitcases, and briefcases at airports and at other secure installations. Of particular concern in the development of such systems has been the detection of concealed weapons, explosives or drugs whose transport is restricted. Unfortunately, many of these illicit materials do not conform to an easily identifiable shape and are not visually detectable in the currently used systems. In particular, many types of explosive materials can be molded into any shape and are not detectable by standard x-ray equipment. Typically, a conveyor transports the items to be inspected into and out of a chamber positioned between an x-ray source. The x-ray source, which comprises a shaped x-ray beam, irradiates the object of interest. Then an array of detectors is used to measure the transmitted intensity. A monitor displays an image of these scanned items. The outline is visually inspected to determine the presence of the objects of concern. This type of conventional x-ray imaging system provides good spatial resolution but is not capable of determining the intrinsic chemical composition of the items in the cargo passing through.